The invention relates to a method and a system for analyzing interlinked production processes for manufacturing a product, such as a motor vehicle.
In the operation of automated production plants, for example production plants in vehicle manufacture, attempts have been made to improve production by controlling the multiplicity of interlinked production processes in an optimum manner with regard to high flexibility and variable capacity.
Production processes comprise, in particular, material, technical, organizational and/or personnel-related transformation processes with added value. In this case, not only material-oriented and/or energy-oriented factors but also temporal and/or monetary factors are important.
Production aim, for example fault-free production or production which maximizes profit, various methods for determining planning or production strategies are known. For example, the article entitled “A Stochastic Programming Approach for Supply Chain Network Design Under Uncertainty” by Santoso et al. (Technical Report, School of Industrial & Systems Engineering, Georgia Institute of Technology, 2003) discloses an analysis of interlinked production processes. The disadvantage of the known analysis of interlinked production processes is that capacity adjustments, site changes, changes in demand, capacity decisions, product assignment decisions are not taken into account at the same time. In addition, standard commercial target variables and temporal interactions between periods are also disregarded. This is due to, inter alia, the great complexity of interlinked production processes and the large number of changes and adjustments to, and decisions regarding, both technical and material, monetary, organizational, personnel-related and temporal factors. The possibility of analyzing the processes is therefore very limited and it is virtually impossible to perform this analysis in a manual fashion.
Therefore, exemplary embodiments of the invention provide methods and systems for analyzing interlinked production processes for manufacturing a product, such as a motor vehicle.
In accordance with the present invention, an exemplary method involves the steps of:                a) acquiring static and dynamic input data for at least one product parameter and/or a process parameter using a data processing unit,        b) determining at least one degree of freedom of one or more product parameters and/or process parameters,        c) acquiring at least one target parameter for at least one product parameter and/or process parameter,        d) processing the acquired static and dynamic input data for the relevant product parameters and/or process parameters on the basis of at least one degree of freedom and automatically adjusting at least one of the product parameters and/or process parameters,        e) at least some of the data determined and acquired in steps a) to d), such as input data, product parameters, process parameters and/or target parameters, are stored and/or output.        
The advantage of the inventive method for analyzing interlinked production processes for manufacturing one or more products is that the method is subdivided into individual steps in which data and parameters associated with different properties are processed in different directions with different degrees of freedom with regard to one or more target parameters. It is advantageous, in particular, that so-called MIP optimization (MIP=Mixed Integer Programming) may be employed, which ensures integrated modelling of the interlinked production processes with temporal, monetary, technical, material and/or organizational factors and their optimum configuration. Such modelling makes it possible to considerably reduce the amount of planning needed for production systems and production processes. In particular, current and/or future production processes can be analyzed and adjusted within a very short space of time by acquiring associated input data. As a result, production strategies can be automatically generated for complex interlinked production processes. In this case, additional parameters, in particular economic and/or monetary additional parameters, such as depreciation, depreciation periods, start-up losses, legal provisions, organizational, technical, temporal, product-specific, process-specific and/or material changes, for example workforce flexibility, production capacity changes, can be taken into account. In addition, such integrated analysis and modelling of all interlinked production processes enables a high level of traceability and transparency in production planning as a result of structured data management and the use of simple mathematical optimization methods.
In a first possible configuration of the invention, steps a) to e) can be carried out iteratively and the data determined in a respective iteration can be compared with one another. At least one of the product parameters and/or process parameters can be expediently adjusted using the comparison of data from different iterations. For example, predicted data for future periods and instantaneous data, the approximation of which can be used to generate optimum production strategies for short-term, medium-term and/or long-term periods, can be acquired as the input data.
In another configuration of the invention, technical capacities, for example available raw materials, product components, vehicle parts, at least one product requirement, for example the instantaneous and/or future demand, instantaneous and/or future market data, demand for a series, desired product extras, product changes, for example instantaneous and/or future product versions, possible product combinations, possible dual uses, are predefined as product parameters. Alternatively or additionally, one or more production sites, for example the number of product lines and/or production areas, organizational capacities, for example available shifts, available production lines and/or production areas, available production line flexibility, available tool capacity, utilization, dual use or reuse of production areas, conversion, construction and/or interlinking of product lines, and/or personnel-related capacities, such as workforce capacity, workforce flexibility, can be predefined as process parameters.
In this case, the number of predefined product and/or process parameters is reduced to a number of indicative production and/or process parameters. That is to say, those parameters which achieve a particular and desired effect are determined and predefined as product and/or process parameters for the integrated analysis and modelling of the interlinked production processes. For example, a multiplicity of product and/or process parameters may be stored in the form of standard parameters or variables, a reduced number of product and/or process parameters, which indicate a predefinable target parameter, being determined, selected and/or predefined from the multiplicity of stored product and/or process parameters on the basis of the relevant target parameter. Taking into account only indicative product and/or process parameters in this manner considerably reduces the number of required parameters and auxiliary conditions to be generated in the integrated analysis and modelling of the interlinked production processes. In addition, the complexity of the integrated analysis and modelling is simplified to a considerable extent. Parameters, such as “transport links” and “product/partial product links”, are thus predefined and taken into account when determining, for example, process links.
Depending on the kind or type of parameter, the associated data are predefined in different ways. The data for the product and/or process parameters are preferably subdivided into two groups of values. On the one hand, the data may be predefined as analogue values or constant values, for example analogue values of transport volumes and production volumes. On the other hand, the data may be predefined in the form of discrete values, for example discrete values for capacity levels (=0/1). For example, the value predefined for the parameter “transport link to the market/end customer/dealer” only for permissible product combinations, production line combinations and possible market combinations is a discrete value of, for example, “zero” for impermissible and “one” for permissible. A value for one of the selected or predefined parameters may also be predefined or determined only when this parameter is relevant to the current analysis on the basis of other indicative parameters, for example if there is a demand for the relevant combination, for example a market and product combination, in the respective period of time.
In this case, the number of discrete parameters decisively determines the complexity of the analysis and modelling. The product and/or process parameters are preferably predefined as analogue parameters. Discrete parameters, for example “stage switch” and “switch link”, whose states are described in the form of discrete “on”/“off” or “activated”/“deactivated” values, can usually be defined as constant and analogue by appropriately combining them with other parameters, in particular with the target parameter and/or other product and/or process parameters, with predefinable auxiliary or additional conditions, as a result of which the outlay, in particular the temporal outlay, on the analysis and modelling of the interlinked production processes is considerably reduced.
In another aspect of the invention, at least one temporal variable, for example a period, a product distribution and/or line occupancy in each period, one product-related variable, for example an assignment of products to production lines and/or production areas, and/or one capacity-related variable, for example dynamic adjustment of organizational, technical and/or personnel-related capacities, in particular investments, production of one or more different series on one or more production lines, dual use or reuse of production lines and/or production areas, can be predefined as degrees of freedom.
For further simplification and/or restriction of the analysis and modelling, the latter can be carried out for a predefinable period of time. In this case, at least one of the product parameters and/or process parameters can be additionally adjusted for a predefinable period of time. This makes it possible to generate a production strategy in a particularly flexible and variable manner.
In another advantageous configuration of the invention, at least one of the product parameters and/or process parameters is acquired and adjusted monetarily. As a result, primary or secondary economic aspects, such as added value, loss, profit, can also be taken into account, analyzed and/or assessed, in addition to primary technical, material-oriented, product-related and organizational aspects, when generating production strategies.
In addition, limit values, for example limit capacities, and/or standard values, for example models of working hours, shift models, personnel master data, can be predefined for at least one of the product parameters and/or process parameters. The use of standard values and/or limit values makes it possible to carry out the analysis and modelling in a quick and simple manner.
Furthermore, in another aspect of the invention, at least one of the acquired and/or adjusted product parameters and/or process parameters can be assessed and output. For example, differences between generated analyses, models, concepts, their cost-effectiveness, in particular the cost-effectiveness of individual parameters or a plurality of parameters, if appropriate in combination with one another, for example unit cost advantages, utilization, delivery capacity, can thus be determined and assessed, for example by means of a simple comparison. The method for analyzing interlinked production processes can also be used to determine capacity and/or flexibility variables and production strategies.
Depending on the stipulation, at least one of the acquired and/or adjusted product parameters and/or process parameters can be output individually, in combination and/or in relation to one another, for example in the form of a graph. The graph can be, for example, a cost/time graph, a cost/capacity graph and/or a capacity/time graph.
The inventive system for analyzing interlinked production processes for manufacturing at least one product, in particular a motor vehicle, comprises a predefinable number of modules which are described by way of example below using their functions:                a) a module that acquires static and dynamic input data for at least one product parameter and/or process parameter,        b) a module that determines at least one degree of freedom of one or more product parameters and/or process parameters,        c) a module that acquires at least one target parameter for at least one product parameter and/or process parameter,        d) a module that processes the acquired static and dynamic input data for the relevant product parameters and/or process parameters on the basis of at least one degree of freedom and for automatically adjusting at least one of the product parameters and/or process parameters,        
e) a data memory that stores, and/or at least one output means for outputting, at least some of the data determined and acquired in steps a) to d), such as input data, product parameters, process parameters and/or target parameters, the modules being stored in a data processing unit and being able to be controlled and executed by a computer program implemented in said data processing unit.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.